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1、 W - - - - - - - - - 7 7 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - W W D - w - - - - EN 723:2009 (E) 2 Contents Page Foreword 3 1 Scope 4 2 Terms and definitions .4 3 Principle 4 4 Preparation of samples and test pieces 4 4.1 Preparatory procedures 4 4.1.1
2、 General 4 4.1.2 Residual carbon content .5 4.1.3 Total carbon content .5 4.1.4 Potential carbon content .5 4.2 Preparation of samples .5 4.2.1 Tubes 5 4.2.2 Fittings 5 4.3 Cleaning of sample surfaces 5 4.3.1 Cleaning of inner surface of sample 5 4.3.2 Cleaning of outer surface of sample6 4.4 Prepar
3、ation of test pieces .7 4.4.1 Tubes 7 4.4.2 Fittings 8 5 Method for carbon content determination 9 5.1 General 9 5.2 Determination of the carbon content 10 5.3 Determination of the blank value 10 6 Expression of results . 10 7 Calibration . 11 8 Test report . 11 Bibliography . 12 EN 723:2009 (E) 3 F
4、oreword This document (EN 723:2009) has been prepared by Technical Committee CEN/TC 133 “Copper and copper alloys”, the secretariat of which is held by DIN. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the l
5、atest by October 2009, and conflicting national standards shall be withdrawn at the latest by October 2009. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or al
6、l such patent rights. This document supersedes EN 723:1996. In comparison with the first edition of EN 723:1996, the following significant technical changes and one significant editorial change were made: improvement of the accuracy of the method; extension of the scope of the standard to fittings o
7、f copper alloys; simplification by limitation to only one method for carbon content determination, namely that of infrared absorption spectrometry: Method using tetrabutylammonium hydroxide (HTBA) and Method of determination by measurement of differential electrical conductivity (coulometric) delete
8、d; simplification by limitation to only one cutting method for tubes with diameters exceeding the furnace diameter by deletion of the “longitudinal cutting method“; change of Clause 2 “Normative References“ into “Bibliography“ with renumbering. According to the CEN/CENELEC Internal Regulations, the
9、national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norw
10、ay, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. EN 723:2009 (E) 4 1 Scope This European Standard specifies a combustion method for determining the carbon content, if any, on the inner surface of tubes of copper or fittings of copper or copper all
11、oys. This standard applies only to seamless, round copper tubes as specified for example in EN 1057 and EN 13348 or fittings of copper or copper alloys as specified in EN 1254 (all parts). 2 Terms and definitions For the purposes of this document, the following terms and definitions apply: 2.1 resid
12、ual carbon CR carbon present in the chemical form of elemental carbon 2.2 potential carbon CP carbon present in the chemical form of organic compounds EXAMPLE Organic compounds: oils, greases, etc. 2.3 total carbon CT sum of residual carbon and potential carbon 3 Principle Combustion of the carbon p
13、resent on the inner surface of a tube or fitting sample, carried out at a given temperature in an oxygen flow. Determination, by infrared absorption spectrometry, of the residual or total carbon content, or both, by measurement of the carbon dioxide generated. Calculation of potential carbon content
14、 is by subtraction of the residual carbon content from the total carbon content. 4 Preparation of samples and test pieces 4.1 Preparatory procedures 4.1.1 General Carry out the procedures in 4.1.2, 4.1.3 or 4.1.4 depending on the carbon to be determined and taking account of the following precaution
15、s: a) metal cutting tool shall be free from protective paint; b) clamps shall be flat and consist of copper, aluminium, steel or an alternative material. Alternative materials shall not be detrimental to their cleanliness; EN 723:2009 (E) 5 c) all tools and implements used for cutting or clamping sa
16、mples shall be degreased before sample preparation; d) degreasing shall be done by wiping with a lint-free cloth containing absorbed tetrachloroethylene, trichloroethylene or trichloroethane or, because of potential for environmental harm, other solvents of equivalent performance, e.g. acetone. Thes
17、e solvents shall also be used for cleaning/immersion of samples where appropriate; e) suitable protective gloves should be used to ensure skin contact with the surface under test is avoided; f) between the cleaning operation and the combustion operation, the test pieces shall be kept in a non- conta
18、minating environment, such as a clean laboratory or in a desiccator containing sodium hydroxide pellets. The tests shall be completed within approximately 5 h of cleaning the sample, or if not, the sample shall be re-cleaned. 4.1.2 Residual carbon content a) prepare samples (see 4.2); b) clean inner
19、 and outer surface of sample (see 4.3.1 and 4.3.2); c) prepare test pieces (see 4.4). 4.1.3 Total carbon content a) prepare samples (see 4.2); b) clean outer surface of sample (see 4.3.2); c) prepare test pieces (see 4.4). 4.1.4 Potential carbon content Prepare separate samples and test pieces follo
20、wing the procedures in 4.1.2 and 4.1.3. 4.2 Preparation of samples 4.2.1 Tubes Cut a sample approximately 30 cm long from a tube, using a metal-cutting saw or a pipe cutter. Deburr the outer and inner edges of the sample ends, using a smooth file or a trimming blade, take care that any burrs removed
21、 do not fall into the bore of the tube. 4.2.2 Fittings Select sufficient fittings from the batch in order to be able to cut test pieces from them having a minimum total internal surface area of 10 cm2. 4.3 Cleaning of sample surfaces 4.3.1 Cleaning of inner surface of sample The following steps shal
22、l be performed in a fume cupboard. Immerse the sample, for a minimum of 2 min in an agitated bath of boiling chlorinated solvent, for example, analytical grade trichloroethylene or trichloroethane, that shall be used as reference in case of dispute ensuring that the solvent baths are kept topped up,
23、 such that the sample remains totally immersed in the solvent. Immerse the sample in a second, boiling solvent bath for at least 30 s. EN 723:2009 (E) 6 Remove the sample from the bath and place it vertically under a fume hood or on a grease-free plate in an oven operating at a temperature of at lea
24、st 80 C for a minimum of 60 s, until the solvent has totally evaporated. Refresh both baths periodically, as appropriate, in accordance with written internal procedures. 4.3.2 Cleaning of outer surface of sample 4.3.2.1 General Degrease the outside surface of the sample by wiping with a clean, lint-
25、free, solvent-containing cotton cloth, taking care to ensure that no fibres remain on the sample after wiping. Clean the sample by chemical cleaning method, see 4.3.2.2, or for tubes in R250 and R290 material conditions1) only, the alternative mechanical cleaning method, see 4.3.2.3, except in cases
26、 of dispute or preparation for blank value determination, may be used. 4.3.2.2 Chemical cleaning 4.3.2.2.1 Sealing a) For annealed tubes only: Squashing/flattening a 20 mm (approx.) portion of the tube extending from one end, between clamps (see 4.1) placed between the jaws of a vice. The squashed e
27、nd is then folded over and also squashed/flattened against the adjacent, 20 mm (approx.) length of tube, again using clamps (see 4.1) fixed between the jaws of a vice. This method shall be used for reference testing. b) For tubes or fittings: Seal one tube end or all fitting ends by inserting approp
28、riately-sized, silicone or neoprene plugs. NOTE If necessary, the ends of tubes in annealed material condition should firstly be re-rounded using an appropriate, degreased re-rounding tool, in order to obtain a leak-tight seal with the plug. 4.3.2.2.2 Cleaning Place the degreased sample in a clean b
29、eaker containing fresh diluted nitric acid for half starting from 50 % concentrated nitric acid. The temperature of the acid shall be at least 20 C and for handling reasons, care has to be taken to control the exothermic reaction, if necessary by cooling the beaker. a) For tubes: The beaker shall co
30、ntain sufficient solution to cover between 75 mm and 125 mm of the length of the sample (the smaller the diameter of the tube being tested, the greater the depth of immersion required to ensure a sufficiently covered surface area). b) For fittings: The beaker shall contain a sufficient quantity of s
31、olution to cover the sample. Refresh the acid bath weekly or after preparation of about forty samples (whichever is the sooner). 1) see EN 1173 for the explanation of R250 and R290. EN 723:2009 (E) 7 Ensure that the sample remains in the acid solution for at least 30 s so that copious quantities of
32、brown fumes (NO2) are expelled. This step of operation shall be performed in a fume cupboard. Withdraw the sample from the acid solution and rinse thoroughly with deionised water. Transfer the sample to a bath containing boiling deionised water for a duration between 30 s and 60 s, which, before use
33、 shall have been boiled for approx. 5 min to ensure a complete degassing of the water, or rinse the sample with hot (min. 50 C) running water for at least 30 s. Take care to ensure that the useful part of the sample is fully immersed in the water bath. Due to an uptake of CO2 from the air, refresh t
34、he deionised water every day or after the preparation of about forty samples (whichever is sooner). Remove the sample from the bath and place it vertically under a fume hood or on a grease-free plate in an oven operating at a temperature of at least 80 C for a minimum of 60 s, until the water has to
35、tally evaporated or let it dry on air. 4.3.2.3 Mechanical cleaning Hold the tube in a vice and remove all traces of the outer surface in the area to be tested, using a degreased file. Alternatively, a thin layer from the outer surface may be removed by turning on a lathe using a tool with a degrease
36、d tip. All tools used for mechanical cleaning shall be free of organic contamination. The tools shall not be used for other mechanical operation. 4.4 Preparation of test pieces 4.4.1 Tubes 4.4.1.1 General Carry out the procedure given in 4.4.1.2 or 4.4.1.3, depending on the tube diameter, and taking
37、 account of the precautions described in 4.1. 4.4.1.2 Tubes with diameters not exceeding the furnace diameter From the cleaned sample, cut and discard a 2,5 cm length, from one end which, in the case of a chemically cleaned outer surface, shall be from the plugged or flattened end of the tube (havin
38、g firstly removed the plug from the tube end if appropriate). Measure the required length of tube using a clean measuring device to yield an internal surface area between 20 cm2 and 25 cm2. Cut off the required length using either a clean, square-cut auto-saw used only for such purposes or a degreas
39、ed, fine-toothed hacksaw, avoiding overheating the sample. If the test piece is longer than the zone of incandescence of the combustion device described in 5.1 c), cross-cut the test piece into two, in order that both pieces may be fed simultaneously into the zone of incandescence. Take care to ensu
40、re that the cut is square. If using an auto-saw, take also care to ensure that all surfaces with which the tube is in contact are thoroughly degreased. When filing and cutting tubes, take care to ensure that the section of tube being held in position (e.g. between the jaws of a vice) is not excessiv
41、ely distorted. Determine the internal surface area of the test piece from its mean internal diameter and mean length, measured to an accuracy of 0,1 mm. NOTE If the cross-cut leads to a loss of length, it should be taken into account for the surface area determination. EN 723:2009 (E) 8 4.4.1.3 Tube
42、s with diameters exceeding the furnace diameter Prepare the sample as described in 4.4.1.1. If a test piece of internal surface area of at least 20 cm2 can be obtained by flattening, carry out the flattening operation between the jaws of a vice equipped with aluminium or alternative material clamps
43、previously degreased using trichlorethylene or trichloroethane. The alternative material for the clamps shall not be detrimental to their cleanliness. 4.4.2 Fittings 4.4.2.1 General Depending on size, a test piece might be: a) one complete fitting; b) part of one fitting; c) several fittings. The internal surface area of the test piece shall be at least 10 cm2. Prepare test piece(s) by one of the following procedures and afterwards keep the test piece(s) taking account of the precautions desc